A shadow is cast as a stand-in for President Barack Obama speaks at the podium during a rehearsal for a debate at the University of Denver Tuesday, Oct. 2, 2012, in Denver. President Barack Obama and Republican presidential candidate and former Massachusetts Gov. Mitt Romney will hold their first debate Wednesday. (AP Photo/David Goldman)

Five things to watch for when Barack Obama and Mitt Romney meet in their first presidential debate Wednesday night:

1. ROMNEY MAKES HIS MOVE: He needs to re-energize his campaign after slipping in the polls. Can he do it by going on attack? Watch for Romney to lay into Obama's policies with gusto while trying to avoid getting too personal with his criticism, which could backfire. Obama needs to stay calm and hold his ground.

2. OBAMA ON DEFENSE: He's stuck trying to defend a painfully slow economic recovery. Can a sitting president sell the idea that he knows how to make the next four years better than his first four? Or does Obama mostly try to divert attention by slamming Romney's economic plans?

3. ABOUT THAT 47 PERCENT: Romney faces his biggest audience yet in the wake of his remarks about "47 percent of Americans." He'll try to dispel the notion that he's uncaring toward people who depend on government benefits or don't pay income tax. Can he recast his remarks as a critique of an economy that leaves so many needing food stamps and unemployment checks?

4. HOW THEY SAY IT: Watch for a clumsy gesture or errant look that says more than words — remember Al Gore sighing, George H.W. Bush checking his watch. Listen for tone of voice, too. Does Obama come across as arrogant or aloof? Does Romney seem awkward or out of touch? Did that zinger sound natural — or forced? Humor is welcome relief, but it's tricky to pull off.

5. A SURPRISE: They try to prepare for every scenario, but something will catch the candidates off guard. That's the telling moment. How well do they respond? Romney occasionally lost his cool with GOP primary opponents. Obama tends to lapse into long-winded answers and troublesome phrasing. Will either man be flustered into a mistake?